I have quite a few suggestions, because that class doesn't seem quite 'Striker'-ish yet.
First of all - the extra damage only being applied to unarmed attacks is not a good idea, as it severely hampers the Monk's damage output and thus his role as a Striker. Instead, I would change it to simply increasing the damage of your unarmed strikes by one size category, as most of the information I've seen strongly points to you getting extra dice for weapons when you level anyway. Also, this is incredibly underpowered for a monk wielding anything other than his own fists - he will simply not be able to match the firepower of a Rogue, Ranger or Warlock with that ability as written.
My suggestion would be some kind of focus ability, much like the Warlock's curse or Ranger's quarry, which grants the same damage bonus as you already have there, but is tied to a larger selection of monk weapons and is only effective against the chosen foe.
Now for the powers - I don't like Stunning Blow. Triple weapon damage AND stunning a foe, who then requires a save to end, is quite nasty for a 1st level daily. Making it Reliable instead of having a miss effect causes even more of an imbalance, in my mind. I would suggest perhaps lowering the effect to dazing the target, and make the Stunning Blow a higher-level daily, or lowering the damage and making the Stun last until the end of your next turn only.
Also, the ranged powers and Serpent Sweep have requirements that are a bit too specific, and if Shurikens are anything like they were in 3.5 I would advise perhaps adding a Weapon Talent feature, like the Rogue has, and maybe add to this some unarmed strike details. This would reinforce what weapons your stereotypical Monk should be using, but doesn't force them to do so. For example:
Monk Weapon Talent: When attacking with a Shuriken or Unarmed Strike, a Monk increases her damage dice by one size category for all attacks. The Monk also gains a +1 class bonus on attack rolls with her unarmed strike.
As my final contribution I would suggest some 'Ki' abilities, as at the moment you could probably say that's a Martial class. It needs some more Ki flavour, so I suggest the following class feature (or something similar).
Channel Ki: At first level a Monk selects two Channel Ki abilities from below. The Monk may use only one Channel Ki ability per encounter.
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Burning Ki: Free action. The Monk's next attack deals Fire and Weapon damage.
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Diamond Mind: Free action. The Monk may make a saving throw with a bonus equal to her Wisdom modifier.
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Moment of Clarity: Free action. The Monk's next attack roll gains a bonus equal to the Monk's Wisdom modifier.
Add abilities/change names until satisfied.
I hope you like my suggestions
